The testes are internal male reproductive organs. A normal male has two testicles, located on the left and right side of the scrotum. The testicles are oval in shape and gray in color. In adults, the testicles are 3.5-4.5 cm long, 2-3 cm wide and 1-2 cm thick, and each side weighs 10-15 grams. The left side is usually about 1 cm lower than the right side. Some people have a large and small testicle, one high and one low, if the difference is not large, are normal. There are two main causes of tiny testicles congenital. One is congenital testicular dysplasia, which is caused by chromosomal abnormalities and occurs in about one in 400 male infants. This kind of patients mostly see delayed puberty development, male secondary sexual characteristics are not obvious, and 80% of patients can show feminization such as breast enlargement. The treatment of this disease is mainly to supplement androgens to restore the male physique and maintain the sexual function of the patient. Another type of congenital adrenal hyperplasia is the large increase of androgens synthesized in the adrenal glands, which inhibits the secretion of gonadotropins by the pituitary gland and thus inhibits testicular development. In this case, the patient shows precocious puberty, with male secondary sexual characteristics appearing before the age of 10, but the testes are still small. Cortisone treatment is used abroad to lower plasma androgens so that the testes can develop. The causes of testicular atrophy and small size are complicated by acquired factors. The common ones are: 1. Trauma, accident or surgery causing testicular damage. 2. 2. Mumps during adolescence with testicular inflammation. 3, suffering from varicocele. 4.The testicles are exposed to X-rays for a long time. 5.Underwear is too tight or hot water bath is too frequent, which interferes with the function of temperature regulation in the scrotum. 6, suffering from endocrine diseases. 7.Nutritional deficiency. 8.Environmental pollution. 9, taking drugs that damage the testicles. 10, long-term excessive smoking, drinking alcohol, etc.